1. Technical Field
The invention relates generally to input-output calibration, and more particularly, to methods for input-output calibration and image rendering.
2. Related Art
With an input device and an output device, a processing unit should be able to facilitate vision-based interaction between a user and visual content displayed for the user. For example, the input device can be a camera that captures images of the user for the processing unit; the output device can be a display device that display the visual content rendered by the processing unit. The output device can display the visual content on a screen.
If the spatial relationship between the camera and the screen is not fixed, the processing unit must first determine the position of the screen with respect to the camera. A process devised for this purpose can be referred to as an input-output calibration process or a screen-camera calibration process. The process is relatively easy if the camera can see the screen directly. It is more difficult but should be achievable if the camera can see the screen indirectly through a reflective surface.
The camera sometimes is placed adjacent to the screen and facing the user in order to sense all the possible postures, gestures, or lines of sight, of the user by capturing image(s) of the user. However, in such a position, the camera may not see the screen directly or indirectly. Under the circumstances, an unconventional process is needed to facilitate input-output calibration.